Stihl chainsaw starts then dies—common fixes (5 pro tips)
“Give me six hours to chop down a tree and I will spend the first four sharpening the axe.” – Abraham Lincoln
As someone who’s spent countless hours in the woods, wrestling with logs, and coaxing reluctant chainsaws to life, I understand the frustration of a Stihl chainsaw that starts then dies. It’s a common problem, but often solvable with a bit of know-how. In this guide, I’ll share five pro tips, gleaned from years of experience, to help you diagnose and fix this issue. We’ll cover everything from fuel problems to ignition issues, and I’ll sprinkle in some personal anecdotes and technical insights along the way. Whether you’re a seasoned logger or a weekend warrior prepping firewood, these tips will help you keep your Stihl chainsaw running smoothly.
Stihl Chainsaw Starts Then Dies: 5 Pro Tips for a Quick Fix
A chainsaw that starts but quickly dies is a frustrating experience, especially when you have a pile of wood to cut. This issue can stem from several causes, and understanding the potential culprits is the first step toward resolving the problem.
Before diving into specific fixes, let’s define some key terms that will be used throughout this guide:
- Green Wood: Freshly cut wood with a high moisture content (typically above 30%). It’s harder to split and burns poorly.
- Seasoned Wood: Wood that has been allowed to dry, reducing its moisture content to around 20% or less. It’s easier to split and burns much more efficiently.
- Carburetor: A device in the chainsaw engine that mixes air and fuel to create a combustible mixture.
- Spark Plug: An electrical component that ignites the air-fuel mixture in the engine cylinder.
- Air Filter: A filter that prevents dust and debris from entering the engine.
- Fuel Filter: A filter that prevents contaminants from entering the carburetor.
Tip 1: Fuel System Issues: The Prime Suspect
The fuel system is often the first place to look when a chainsaw starts then dies. Issues within the fuel system can lead to the engine not getting a consistent and adequate supply of fuel.
Identifying Fuel Problems
The most common fuel-related problems include:
- Old or Contaminated Fuel: Fuel degrades over time, especially when mixed with oil. This can lead to gumming up the carburetor and fuel lines.
- Clogged Fuel Filter: A dirty fuel filter restricts fuel flow, starving the engine.
- Ventilation Issues: The fuel tank needs to be properly vented to allow fuel to flow freely.
- Carburetor Problems: A dirty or improperly adjusted carburetor can cause the engine to stall.
Step-by-Step Solutions
- Check the Fuel:
- Smell Test: Fresh fuel should have a distinct, sharp odor. If it smells stale or sour, it’s likely old.
- Visual Inspection: Look for sediment or discoloration in the fuel.
- Action: If the fuel is old or contaminated, drain the tank and replace it with fresh, high-quality fuel mixed with the correct ratio of two-stroke oil (usually 50:1 for Stihl chainsaws). I always recommend using a fuel stabilizer, especially if you don’t use your chainsaw regularly. I had a bad experience where I ruined a carburetor because I didn’t stabilize the fuel properly. Now it is a must for me.
- Inspect and Replace the Fuel Filter:
- Location: The fuel filter is usually located inside the fuel tank, attached to the end of the fuel line.
- Inspection: Remove the filter and inspect it for clogs or debris.
- Action: If the filter is dirty, replace it with a new one. Stihl fuel filters are relatively inexpensive and should be replaced annually, or more often if you’re cutting in dusty conditions.
- Check the Fuel Tank Vent:
- Location: The vent is usually a small hole or valve on the fuel tank cap.
- Inspection: Ensure the vent is clear and not blocked by dirt or debris.
- Action: Clean the vent with a small wire or compressed air. A blocked vent can create a vacuum in the tank, preventing fuel from flowing.
- Clean the Carburetor:
- Complexity: This is a more involved process, but often necessary.
- Steps:
- Remove the Air Filter: This gives you access to the carburetor.
- Spray Carburetor Cleaner: Use a high-quality carburetor cleaner to spray into the carburetor throat and any visible jets.
- Reassemble: Reinstall the air filter and try starting the chainsaw.
- Professional Cleaning: If the problem persists, consider taking the chainsaw to a professional for a thorough carburetor cleaning or rebuild.
- Case Study: I once had a Stihl MS 271 that kept stalling. I tried everything, and finally, I took it to a small engine repair shop. The mechanic found that the carburetor was severely gummed up due to old fuel. He cleaned and rebuilt the carburetor, and the chainsaw ran like new. The cost was around $80, but it was well worth it to avoid the hassle of trying to do it myself without the proper tools and knowledge.
Tools and Materials Needed
- Fresh fuel
- Two-stroke oil (Stihl recommends their own brand)
- Fuel filter
- Carburetor cleaner
- Screwdrivers
- Compressed air (optional)
Strategic Advantages
Addressing fuel system issues promptly can prevent more serious engine damage and extend the life of your chainsaw. Using high-quality fuel and oil is an investment that pays off in the long run. Regular maintenance, such as replacing the fuel filter and cleaning the carburetor, can prevent future problems.
Tip 2: Air Filter Inspection and Maintenance
A clean air filter is crucial for proper engine performance. A dirty air filter restricts airflow, causing the engine to run rich (too much fuel, not enough air). This can lead to stalling, poor performance, and increased fuel consumption.
Identifying Air Filter Issues
- Visual Inspection: Check the air filter for dirt, dust, and debris.
- Performance Issues: Notice if the chainsaw lacks power or stalls easily.
Step-by-Step Solutions
- Locate the Air Filter:
- The air filter is usually located under a cover on the side or top of the chainsaw engine.
- Remove the Air Filter:
- Carefully remove the air filter, noting its orientation for reinstallation.
- Clean the Air Filter:
- Foam Filters: Wash with warm, soapy water, rinse thoroughly, and allow to air dry completely.
- Felt or Paper Filters: Tap gently to remove loose dirt, or use compressed air to blow the dirt out from the inside.
- Inspection: Check for damage or tears. If the filter is damaged, replace it.
- Reinstall the Air Filter:
- Ensure the filter is properly seated and the cover is securely fastened.
- Personal Experience: I once neglected the air filter on my Stihl MS 170 for too long. It got so clogged that the engine wouldn’t even start. After cleaning the filter, the chainsaw fired right up and ran much smoother. This taught me the importance of regular air filter maintenance.
Tools and Materials Needed
- Screwdriver (if needed to remove the air filter cover)
- Warm, soapy water (for foam filters)
- Compressed air (optional)
- Replacement air filter (if necessary)
Strategic Advantages
Maintaining a clean air filter improves engine performance, fuel efficiency, and extends the life of the engine. It’s a simple task that can make a big difference. I recommend checking the air filter every time you refuel the chainsaw.
Tip 3: Spark Plug Examination and Replacement
The spark plug is responsible for igniting the air-fuel mixture in the engine cylinder. A faulty spark plug can cause the engine to start hard, run poorly, or stall completely.
Identifying Spark Plug Issues
- Hard Starting: The chainsaw is difficult to start.
- Poor Performance: The engine lacks power or runs erratically.
- Visual Inspection: The spark plug is fouled, cracked, or corroded.
Step-by-Step Solutions
- Locate the Spark Plug:
- The spark plug is usually located on the side of the engine cylinder, under a rubber boot.
- Remove the Spark Plug:
- Pull off the rubber boot.
- Use a spark plug wrench to unscrew the spark plug.
- Inspect the Spark Plug:
- Electrode Condition: The electrode should be clean and dry. A black, oily electrode indicates a rich fuel mixture. A white, ashy electrode indicates a lean fuel mixture.
- Cracks or Damage: Check for cracks in the ceramic insulator or damage to the electrode.
- Gap: Use a spark plug gap tool to check the gap between the electrode and the ground strap. The correct gap for Stihl chainsaws is usually around 0.020 inches (0.5 mm).
- Clean or Replace the Spark Plug:
- Cleaning: If the spark plug is only slightly fouled, you can clean it with a wire brush or spark plug cleaner.
- Replacement: If the spark plug is heavily fouled, cracked, or damaged, replace it with a new one. Use the correct spark plug for your Stihl chainsaw model.
- Reinstall the Spark Plug:
- Screw the spark plug in by hand until it’s snug.
- Tighten it an additional quarter turn with the spark plug wrench.
- Reattach the rubber boot.
- Data Point: I’ve found that replacing the spark plug annually, even if it looks okay, can improve the overall performance of my chainsaws. It’s a cheap and easy way to ensure reliable starting and smooth running.
Tools and Materials Needed
- Spark plug wrench
- Spark plug gap tool
- Wire brush or spark plug cleaner
- Replacement spark plug (correct type for your chainsaw model)
Strategic Advantages
A properly functioning spark plug ensures efficient combustion and reliable engine performance. Regular inspection and replacement can prevent starting problems and extend the life of the engine.
Tip 4: Exhaust System Check: Clearing the Path
A clogged or restricted exhaust system can cause the engine to overheat and stall. The exhaust system allows the engine to expel exhaust gases, and if it’s blocked, the engine can’t breathe properly.
Identifying Exhaust System Issues
- Overheating: The engine gets excessively hot.
- Loss of Power: The engine lacks power and struggles to maintain speed.
- Visual Inspection: Check the exhaust port and spark arrestor for carbon buildup.
Step-by-Step Solutions
- Locate the Exhaust Port and Spark Arrestor:
- The exhaust port is usually located on the side of the engine cylinder.
- The spark arrestor is a small screen located at the end of the muffler.
- Remove the Spark Arrestor:
- Use a screwdriver or wrench to remove the spark arrestor.
- Inspect the Spark Arrestor:
- Check for carbon buildup or clogs.
- Clean the Spark Arrestor:
- Use a wire brush to remove carbon buildup.
- If the spark arrestor is heavily clogged, you can try soaking it in carburetor cleaner overnight.
- Inspect the Exhaust Port:
- Look for carbon buildup in the exhaust port.
- Clean the Exhaust Port:
- Use a small scraper or screwdriver to carefully remove carbon buildup.
- Be careful not to damage the cylinder or piston.
- Reinstall the Spark Arrestor:
- Ensure the spark arrestor is properly seated and securely fastened.
- Original Insight: I discovered that using a small propane torch to burn off carbon buildup on the spark arrestor is a quick and effective cleaning method. Just be sure to do it in a well-ventilated area and avoid overheating the screen.
Tools and Materials Needed
- Screwdriver or wrench
- Wire brush
- Carburetor cleaner (optional)
- Small scraper or screwdriver
Strategic Advantages
Maintaining a clear exhaust system allows the engine to breathe properly, preventing overheating and performance issues. Regular cleaning of the spark arrestor is especially important in areas where spark arrestors are required to prevent wildfires.
Tip 5: Idle Adjustment and Carburetor Tuning
The carburetor controls the air-fuel mixture that enters the engine. Improper carburetor settings can cause the engine to idle poorly, stall, or run rich or lean.
Identifying Carburetor Tuning Issues
- Rough Idle: The engine idles unevenly or stalls.
- Poor Acceleration: The engine hesitates or stumbles when you try to accelerate.
- Black Smoke: The engine is running rich (too much fuel).
- White Smoke: The engine is running lean (not enough fuel).
Step-by-Step Solutions
- Locate the Carburetor Adjustment Screws:
- Most Stihl chainsaws have three adjustment screws:
- L (Low Speed): Controls the fuel mixture at idle and low speeds.
- H (High Speed): Controls the fuel mixture at high speeds.
- LA (Idle Speed): Controls the engine idle speed.
- Most Stihl chainsaws have three adjustment screws:
- Adjust the Idle Speed (LA):
- Start the chainsaw and let it warm up for a few minutes.
- Turn the LA screw clockwise to increase the idle speed or counterclockwise to decrease it.
- Adjust the idle speed until the engine idles smoothly without stalling.
- Adjust the Low Speed (L):
- Turn the L screw in (clockwise) until the engine starts to stumble or stall.
- Then, turn the L screw out (counterclockwise) until the engine runs smoothly.
- The goal is to find the point where the engine runs smoothly without hesitation.
- Adjust the High Speed (H):
- Caution: Adjusting the high-speed screw requires experience and a tachometer. Incorrect settings can damage the engine.
- If you’re not comfortable adjusting the high-speed screw, it’s best to take the chainsaw to a professional.
- Procedure:
- Use a tachometer to monitor the engine RPM.
- Turn the H screw in (clockwise) to lean out the mixture or out (counterclockwise) to richen the mixture.
- Adjust the H screw until the engine reaches the recommended RPM for your Stihl chainsaw model.
- Cost Consideration: I once tried to adjust the high-speed screw on my Stihl MS 291 without a tachometer, and I ended up damaging the engine. The repair cost me over $200. I learned my lesson and now always use a tachometer or take it to a professional.
Tools and Materials Needed
- Screwdriver (small, flat-head)
- Tachometer (optional, but highly recommended for adjusting the high-speed screw)
Strategic Advantages
Proper carburetor tuning ensures optimal engine performance, fuel efficiency, and longevity. It’s a skill that takes practice to master, but it’s well worth the effort. If you’re not comfortable adjusting the carburetor yourself, it’s best to take the chainsaw to a professional.
Additional Tips and Considerations
- Safety First: Always wear appropriate safety gear when working with a chainsaw, including eye protection, hearing protection, gloves, and sturdy footwear.
- Read the Manual: Consult the owner’s manual for your Stihl chainsaw model for specific instructions and recommendations.
- Regular Maintenance: Perform regular maintenance, such as cleaning the air filter, replacing the fuel filter, and inspecting the spark plug, to prevent problems.
- Professional Help: If you’re unable to diagnose or fix the problem yourself, don’t hesitate to take the chainsaw to a qualified repair technician.
Conclusion
A Stihl chainsaw that starts then dies can be a frustrating problem, but with a systematic approach and a little know-how, you can often diagnose and fix the issue yourself. By checking the fuel system, air filter, spark plug, exhaust system, and carburetor settings, you can keep your chainsaw running smoothly and efficiently. Remember to prioritize safety and consult the owner’s manual for specific instructions.
Now that you’ve learned these pro tips, you’re well-equipped to tackle common chainsaw problems and keep your Stihl chainsaw running strong. Get out there, tackle that firewood pile, and enjoy the satisfaction of a job well done!
